Preparation of granules:
wet granulation method:
Diclofenac sodium was
used as a model drug to formulate granules. Starch powder was used as disintegrant, whereas lactose and talc were used as diluent and lubricant respectively. The binder solution was prepared by
dissolving given amount of Ao mucilage as per
particular formulation code (2, 4, 6, 8 and 10 % w/v) in minimum quantity of
water fοr 15 min tο
form а paste-like mаss (dispersion). The
granules were prepared by wet granulation process. The batch size was 200 g.
The drug, lactose, talc and starch were mixed thoroughly, and a sufficient
volume of ~40 ml of 2, 4, 6, 8 and 10 % w/v
of mucilage of Anacardium occidental was added slowly to the
powder blend, and kneading was performed
for ~10 min until formation of wet mass
with enough cohesiveness. The wet mass was forced through a no. 16 sieve (1180
µm) and dried at 50° in a hot air oven
for 8 h. The dried granules were re-sieved through a no. 20 sieve (850 µm). The
composition of the each formulation is given in table 1.
Evaluation
of granules:18-21
The prepared granules
were then evaluated for percentage of fines, particle size, angle of repose,
bulk and tapped densities; compressibility index and total porosity.
Compression
of Tablets:
After performing precompression test on granules the dried granules were
compressed into tablets by using Cadmach (Ahmedabad) single punch machine using flat-faced punches.
The batch size of 200 tablets was prepared.
Evaluation of tablets:
The prepared tablets
were evaluated for general appearance, content uniformity, hardness,
friability, weight variation, thickness, diameter, disintegration time and in
vitro dissolution profile using methods specified in Indian Pharmacopoeia.
The following evaluation tests were carried out on formulated tablets which
includes;
General
appearance:
Two tablets from each
formulation were randomly selected and organoleptic
properties such as colour, odour,
taste, and shape were evaluated.
Thickness and diameter:
Thickness
and diameter of five tablets were measured using vernier
calipers. Five tablets from each formulation were used and average values were
calculated.
Hardness:
For each
formulation, the hardness of five tablets was determined using the Monsanto
hardness tester (Cadmach).
Friability:
The
friability of a sample of 10 tablets was measured using a Friability tester
(Electro Lab). Ten tablets were weighed, rotated at 25 rpm for 4 minutes.
Tablets were reweighed after removal of fines (dedusted)
and the percentage of weight loss was calculated.
Uniformity of weight:
Twenty
tablets were randomly selected from each batch individually weighed, the
average weight and standard deviation of 20 tablets was calculated.
Drug
content:
Twenty tablets were
randomly sampled from each formulation, finely powdered and individually
estimated for the drug content after suitable dilution with phosphate buffer
(pH 7.4) using UV-VIS spectrophotometer (UV-1601, Shimadzu) at 276 nm.
Disintegration
test:
The test was performed
using Disintegration test apparatus by placing each tablet in each basket with
the disc. The process was carried out using pH 7.4-phosphate buffer maintained
at 37°C.
In vitro drug release study:
Drug release study was
carried out using USP dissolution rate test apparatus-II (Electro lab, Mumbai,
India). The study was conducted at 37°C and 50 rpm using 900 ml of pH
7.4-phosphate buffer and studied for drug release up to 90 min. Two ml of
sample was withdrawn at different time intervals, filtered and the drug content
was estimated at 276 nm after suitable dilution.
Stability Studies:
Stability studies were
carried out on optimized formulation as
per ICH specifications. The tablets were stored at 25 ± 2 o C / 60 ± 5% RH and 40
± 2 o C / 75 ± 5% RH for duration of three month. After
an interval of one month samples were withdrawn and tested for various physical
tests and in vitro drug release.
RESULTS
AND DISCUSSION:
Plant products serve
as an alternative to synthetic products because of local accessibility,
environment friendly nature and lower prices compared to imported synthetic
products. Herbs are non-polluting renewable resources for sustainable supplies
of cheaper pharmaceutical products. Today, we have a number of plant-based
pharmaceutical excipients. A number of researchers
have explored the utility of plant-based materials as pharmaceutical excipients. Majority of investigations on natural polymers
in drug delivery systems are centered on polysaccharides and proteins, due to
their ability to produce a wide range of materials and properties based on
their molecular structures.
Physicochemical
Properties of mucilage:
Table 2 shows the
physicochemical parameters of Anacardium
occidental (Ao)
mucilage. The mucilage extracted from the stem of Anacardium
occidental is slightly soluble in water and a dispersion of it yielded a
brown, slimy solution. The gum was practically insoluble in ethanol, ether,
methanol, acetone and chloroform.
The swelling
characteristic of Ao was studied in different media;
0.1N hydrochloric acid, phosphate buffer (pH 7.4) and water. The swelling was
highest in water followed by phosphate buffer and least in 0.1N HCl pH. Generally, the results show that Ao has high swelling index suggesting that the gum may
perform well as binder/disintegrant/matrix forming
agent. The relatively higher swelling index obtained for Ao
at pH 7.4 implies that the gum may be useful as a matrix former in controlled
drug release. Swelling is a primary mechanism in diffusion controlled release dosage
form. The moisture content of Ao was low, suggesting
its suitability in formulations containing moisture sensitive drugs. Given
suitable temperature moisture will lead to the activation of enzymes and the
proliferation of micro organisms, thereby affecting the shelf life of most
routine formulations. It is important to investigate the moisture content of a
material because the economic importance of an excipient
for industrial application lies not only on the cheap and ready availability of
the biomaterial but the optimization of production processes such as drying,
packaging and storage. The total ash and acid insoluble ash value of Ao was found to be 2.0 and 0.5 %w/w respectively. Ash
values reflect the level of adulteration or handling of the drug. Adulteration
by sand or earth is immediately detected as the total ash is normally composed
of inorganic mixtures of carbonates, phosphates, silicates and silica.
Therefore, the low values of total ash and acid insoluble ash obtained in this
study indicate low levels of contamination during gathering and handling of
crude Ao. The bulk and tapped densities give an
insight on the packing and arrangement of the particles and the compaction
profile of a material. The compressibility index and angle of repose of Ao was 20% and 22° respectively, implying that the Ao has a good flow with moderate compressibility. This is
important in scale up processes involving this material as an excipient in a pharmaceutical formulation. Modification of
formulations containing this gum for the improvement of flow properties during
process development will therefore be minimal. A 1% w/v suspension of Ao in water gave a pH of 6.7. The near neutral pH of Ao implies that when used in uncoated tablets, it may be
less irritating to the gastrointestinal tract. It may also find useful
application in formulation of acidic, basic and neutral drugs. Knowledge of the
pH of an excipient is an important parameter in
determining its suitability in formulations since the stability and physiological
activity of most preparations depends on pH.
Stem exudates of Ao yielded 55% of gum when acetone was used for
precipitation of the gum. The mucilage obtained was off white to light brown
powder. The investigation for color change revealed that the presence of
antioxidant does not prevent color change, whereas change in color was found to
be more intense with samples exposed to sunlight.
Acute oral toxicity study:
To
determine the safety level of the extracted Ao
mucilage, acute toxicity and chronic toxicity studies were carried out. In both
toxicity study of the gum revealed no behavioral changes for first four hours
and no mortality, no toxic syndromes were observed even at the dose level
4000mg/kg body weight after 24 hours, indicating the safety of the gum. To
assess the suitability of gum for the oral delivery we have recorded the body
weight profile for the animals during the chronic toxicities at regular
intervals of 10 d. it was found that the body weight of both test and control
and rate of increase were also comparable. Hence it is concluded that chronic
administration of the gum might not influence either the food intake or growth.
Hematological and biochemical parameters that were determined at the end of 30
d of continuous administration were also found to be comparable to that of
control rat. The effect of Ao mucilage on
hematological and biochemical parameters is summarized in table3 and 4
respectively.
Characterization of Drug and excipients:
Differential Scanning Calorimetry (DSC):
The DSC thermogram (Figure 1) of pure diclofenac
sodium showed 2 endothermic peaks. The first small endothermic peak at 630C
was due to water loss. The second sharp endothermic peak at 2880C
and an exothermic peak at 2960C indicated the fusion of the solvated
crystals and the oxidation reaction between diclofenac
sodium and oxygen in air environment fusion, respectively. The DSC analysis of
physical mixture of drug and excipients revealed
negligible change in the melting point of diclofenac
sodium in the presence excipients, indicating no
modification or interaction between the drug and excipients.
Fourier Transform Infrared (FTIR) Spectroscopy:
The
IR spectral analysis of diclofenac sodium and the
physical mixture of diclofenac sodium and other excipients are presented in Figure 2. Pure diclofenac sodium spectra showed principal peaks at 1280
and 1303 cm−1 resulted from C-N stretching and the peak at
1501 and 1571 cm−1 resulted from C=C stretching and C=O
stretching of carboxylate group, respectively.
Confirming the purity of the drug as per established standards. All the above
characteristic peaks appear in the spectra of physical mixture of diclofenac sodium and other excipients,
indicating no modification or interaction between the drug and excipients.
Evaluation of
Granules:
The
granules of different formulations were evaluated for angle of repose, LBD,
TBD, Compressibility index, Hausner ratio, total
porosity and drug content. The results are shown in table 5. The result of
angle of repose (<30) indicate good flow properties of the granules. This
was further supported by lower compressibility index values. The results of
compressibility index indicate a decrease in flowability
with increasing Ao
mucilage concentrations; however, all formulations show good flow properties.
Generally, compressibility index values upto 15%
result in good to excellent flow properties. Granule density, porosity and
hardness are often interrelated properties. In addition, granule density may
influence compressibility, tablet porosity, dissolution and other properties.
The percentage porosity values of the granules ranged from 27.34% to 37.34 %,
indicating that the packing of the granules may range from close to loose
packing and also further conforming that the particles are not of greatly
different sizes. Generally, a percentage porosity value below 26% shows that
the particles in the powders are of greatly different sizes and a value greater
than 48% shows that particles in the powder are in the form of aggregates or
flocculates. The drug content in the weighed amount of granules of all
formulations was found to be uniform. It was observed that the percentage of
fines was reduced as the concentration of mucilage was increased. The
percentage of fines was a little higher in granules prepared using 2% w/v
mucilage as binder. The mean particle size (between 0.42 and 0.45 mm) was found
to be satisfactory for preparation of tablets. Table 5 shows that
the bulk densities of the prepared granules were found to decrease slightly by
increasing concentrations of Ao mucilage. This result
may be due to the formation of larger agglomerates and the decrease in fines in
the granules, as increasing Ao mucilage concentrations provide more binding to the
granules. All these results indicate that the granules possessed satisfactory
flow properties, compressibility and drug content.
Evaluation of tablets:
The
separated mucilage was evaluated for its performance as binder in tablets at
various concentrations (2, 4, 6, 8 and 10 %w/w). Its performance was compared
with starch mucilage at optimum concentration (10% w/w) as standard binder. The
prepared tablets were evaluated for general appearance, thickness, diameter,
weight variation, content uniformity, hardness, friability and disintegration
time. The results are shown in table 6. The shape of the tablets of all
formulations remained circular, odorless and off white color with no visible
cracks. All the formulations showed uniform thickness and diameter. The tablets
showed 96.5-98.1% of the labeled amount of drug, indicating all the batches of
tablets exhibited good uniformity in content. The hardness of tablets increased
with increase in percentage of binding agent used. The tablets prepared with
10% mucilage of Ao
showed more hardness when compared to tablets prepared with 10% starch
mucilage. The percentage friability values were constant in all the batches of
tablets prepared by using different concentrations of mucilage. This mucilage
had given increase in disintegration time with increase in concentration, but
all the values were within pharmacopoeial limits. At
10% concentration, the disintegration time (325 sec) was higher for the tablets
prepared by using 10% Ao mucilage when compared to
starch mucilage ( 275 sec) at 10%. The disintegration time was lesser (250 sec)
for the tablets prepared by using 4% Ao mucilage when
compared to starch mucilage (275 sec) at 10%. The disintegration time (275 sec)
was same for the tablets prepared by using 6% Ao
mucilage when compared to starch mucilage (275 sec) at 10%.
In vitro
release profile:
Comparative
in vitro dissolution profiles is
shown in figure 3 and 4 show that in phosphate buffer pH 7.4 media tablets
prepared by using Ao mucilage had a faster
dissolution than that of starch. At the end of 90 min, 95% release was obtained
from Ao mucilage (at 6% w/w) where the value is 90%
in starch (10%w/w). In both cases the release was almost complete within 90
min. The t50 being less than 40 min. It was found that the drug
release decreased with increase in concentration of mucilage. This study showed
that the drug release from the tablets prepared using mucilage at five
different concentrations was more than 85% in 90 min. These tablets had given
reduced diffusion of drug, since the tablets produced a sticky film of
hydration on the surface. This may be the reason for the reduced dissolution
with increased mucilage concentration.
From
the results of the present study, Ao mucilage may be
used as binding agent in tablet formulations. Ao
mucilage at 6% w/v concentrations shown comparable disintegration and in vitro release to that of starch
mucilage at 10 % w/v. so formulation F3 was considered as optimized
formulation. Ao mucilage at this concentration can be
used for the preparation of uncoated tablets and it can be used in the
formulation of sustained drug delivery system. Since the prepared tablets using
Ao mucilage produced a sticky film of hydration on
the surface, which ultimately reduces drug release rate. Hence Ao mucilage can be evaluated for its efficacy to sustain
the drug release.
Stability studies:
In
order to determine any change on storage, the optimized formulation F2 was kept
at real time (25 ± 2o C / 60 ± 5% RH) and accelerated (40±2 o/75±5%
RH) storage conditions for a period of 3 months. After stability test period,
tablets were analyzed for physical appearance, drug content, hardness,
friability, in vitro release and
disintegration tests. No visible
changes in the appearance of the tablets were observed at the end of the
storage period. The drug content was found to be 96.6% ± 0.03%. There were no significant
changes in friability, hardness, disintegration time and in
vitro dissolution profile( figure 5) after storing for 3 months at both the
temperatures, indicating that the formulation was stable under accelerated
conditions of temperature and humidity. The formulation could provide a minimum
shelf–life of one year. However, a detailed investigation is necessary to
determine the exact shelf- life.
CONCLUSION:
Plant
products serve as an alternative to synthetic products because of local
accessibility, eco-friendly nature and lower prices compared to imported
synthetic products. Natural gums and mucilage have been widely explored as
pharmaceutical excipients. In the present study we
had undertaken to separate mucilage from the stems of Anacardium
occidental Linn . and explore
its use as a tablet binder. From the present study, it was concluded that the
mucilage separated from Anacardium
occidental Linn could be used as a binding agent in the tablet formulations
as it shows very good binding property. The results shown that Ao mucilage at a 6% (w/w) can exhibit good binding
properties comparable to that of 10% (w/w) of starch. The material showed good
gelling property during isolation so it may be studied as a gelling agent as
well as matrix forming agent in sustained release tablets.
ACKNOWLEDGEMENTS:
Authors thank Dr.M.B.Patil,
Principal, KLES College of Pharmacy, Ankola for
providing necessary facilities for conducting the present
work. Authors
also thank Dr.
Reddy’s laboratories, Hyderabad, India for providing gift sample of Diclofenac
sodium.
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Received on
17.08.2009
Accepted on
10.09.2009
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Research
Journal of Pharmaceutical Dosage Forms and Technology. 1(2): Sept.-Oct. 2009,
150-157